Wired Intelligent Edge

Hello,

We have some fiber conections between Procurve switchs. The transceivers are J4859C: http://h30094.www3.hp.com/product/sku/3673146

The fiber between switchs are multi mode OM1 (62.5/125). In the transceiver information web says that it works in both multi and single mode with 1310nm laser wave length. This is the transceiver information in the switchs:

# show interfaces transceiver detail

Transceiver in 25
Interface Index : 25
Type : 1000LX
Model : J4859C
Connector Type : LC
Wavelength : 1310nm
Transfer Distance : 4.0km (9um),

Diagnostic Support : None
Serial Number : XXXXXXXXXX

The multi mode fiber theory says that it only works in 850nm or 1300nm, not in 1310nm wave lenght. 1310nm is for single mode.

So, this is my questions?

1. Is it possible to chanhe the wave lenght of the transceiver laser? If not, is it normal to use 1310nm in multi mode fiber?

2. What about the "Transfer Distance"? What does it means the "4.0km (9um)"? 9um is normally asigned to single mode fiber.

We installed 3 fiber connection, in one of them we have CRC errors:

# show logging -r
Keys: W=Warning I=Information
M=Major D=Debug E=Error
---- Reverse event Log listing: Events Since Boot ----
W 01/21/15 11:12:42 00329 FFI: port 25-Excessive CRC/alignment errors. See help.
W 01/21/15 11:09:17 00329 FFI: port 25-Excessive CRC/alignment errors. See help.

Could we change the transceivers to work in a multi mode fiber?

I will appreciate any help.

Kind regards.

Hello,

that is what configurator and quick specs say about using LX transceiver with multimode cable...

Gigabit LX-LC Mini-GBIC provides a full-duplex Gigabit solution up to 10 km over singlemode fiber, or up to 550 meters over multimode fiber.

o    2-550 m (multimode 62.5 µm core diameter, 500 MHz*km bandwidth) 4
o    2-550 m (multimode 50 µm core diameter, 400 MHz*km bandwidth)  4
o    2-550 m (multimode 50 µm core diameter, 500 MHz*km bandwidth) 4
o    2-10,000 m (singlemode fiber) 5

The fourth note says:

 4.    When using the LX Mini-GBIC in 50 µm or 62.5 µm multimode fiber (MMF) operation, a mode-conditioning patch cord may be required at each end of the link.

Or if you want to rather change transceivers then SX transceivers (J4858C) are primarily used for multi mode applications

BR,

Jan

Thanks for the help.

Kind regards.

You are welcome...

Just another tip... you wrote that only one of three connections logs these errors. Are the other two's the same - using LX, same MM cable and quality and same distance? Maybe these errors could be connected with bad or faulty cable.

BR,

Jan

Yes, the other two links have same hardware with same fiber with similar lenght (350 meters).

I disconnect the fiber and connect again and there is no new CRC errors in one day. I will check the logs.

Regards.

OK. And about changing LX and SX transceivers, you specified the lenght (cca 350m) and you have old OM1 cables so in this case the SX transceivers are not the supported solution.

HP X121 1G SFP LC SX Transceiver (J4858C)

Maximum distance:

2-220 m (62.5 µm core diameter, 160 MHz*km bandwidth
2-275 m (62.5 µm core diameter, 200 MHz*km bandwidth
2-500 m (50 µm core diameter, 400 MHz*km bandwidth)
2-550 m (50 µm core diameter, 500 MHz*km bandwidth)
 

Thanks!